Infrared surface heater

ABSTRACT

The infrared surface heater of the invention comprises a longitudinal housing serving also as a reflector and having mounted therein in a common plane a plurality of quartz tubes arranged parallel to each other and having dissimilar heating powers so as to radiate heat of different wavelengths.

United States Patent [72] Inventors Albert Heidler Erbach, Rhelngau; Woll Dieter Klaus, Finthen kreis Malnz, both of Germany [21 Appl. No. 884,267

[22] Filed Dec. 11, 1969 [45] Patented Dec. 14, 1971 [73] Assignee Thermal Quarr-Schmelze G.m.b.l-l.

Wiesbaden-Biebrich, Germany [54] INFRARED SURFACE HEATER 6 Claims, 8 Drawing Figs.

[52] U.S. Cl 219/553, 219/347, 219/354, 219/411, 219/464, 219/544 [51] lnt.C| H05b3/18 [50] Field olSearch 219/552-553. 354, 411, 543, 547, 458 -468, 544; 338/268, 299, 319

[56] References Cited UNITED STATES PATENTS 3,500,444 3/1970 Hesse et al.1 219/544 3,515,853 2/1970 McAdams 219/411 X 3,541,293 11/1970 MacDonaldetal.

Primary Examiner-Valodymyr Y. Mayewsky AnorneySinger, Stern & Carlberg ABSTRACT: The infrared surface heater of the invention comprises a longitudinal housing serving also as a reflector and having mounted therein in a common plane a plurality of quartz tubes arranged parallel to each other and having dissimilar heating powers so as to radiate heat of different wavelengths.

, III-am ,xmu 1 [1r 2 FIG] FIGA

INVENTORS' E rm @N k). 8D 3 Wm Z WA n WWW A a 1 INFRARED SURFACE HEATER The inventionrelates to an infrared surface radiator which is equipped with electrically heated quartz tubes.

Infrared surface radiators made of quartz have been used already for a considerable length of time for heating flat articles, such as for example, continuously moving plastic webs or paper webs and lacquered surfaces, but also for heating stationary plastic foils and plates, which for instance, are

I processed in vacuum molding machines. The foils or plates in this type of processing are horizontally clamped in position and are then heated by the mentioned infrared surface radiators, for instance, to temperatures between 40 and 120 C. and thereafter are drawn by a vacuum into a mold in which the articles cool off. The molding of the heated foils or plates may also be accomplished by compressed air or by forming dies. At any rate, it is important in this connection that the foils or plates, respectively, are brought as quickly as possible uniformly and economically to the raised deformation temperature which is the proper one for the material of the foil to be deformed.

The quartz radiators employed heretofore for the mentioned purpose have either the form of individual tubes which are heated by electrical coiled heating filaments inserted in the tubes, or the radiators consist of quartz plates which are mounted in a housing, whereby the rear face of this quartz plate is heated by a heating coil. Of late there have been developed quartz surface radiators in which a housing which also serves as a reflector is equipped with a plurality of electrically heating quartz tubes which are spaced from each other and all of which have the same temperature.

Most of the plastic materials which come into consideration for a thermic deformation absorb the largest portion of the quartz tube radiation which normally is in the wavelength range of L to 4.5 with an average of 2.3 so that a good efficiency of the heat is assured.

The object of the present invention is an infrared surface radiator provided with electrically heated quartz tubes which for all plastics coming into consideration produce favorable absorption and a good efficiency.

. In accordance with the present invention, this object is attained in that a housing is provided with a plurality of quartz tubes with dissimilar heating powers so that each tube produces a radiation of different wavelength.

For practicing this invention, two possibilities could be employed. Firstly, the quartz tubes may be provided with heating filaments of dissimilar heating power or secondly one employs directly or indirectly heated quartz tubes. In the second case, the quartz tubes provided with heating filaments are used to indirectly heat quartz tubes which have no heating filaments in their interior, so that the quartz tubes with no heating filaments produce their own radiation having a low temperature. It is advisable to arrange the quartz tubes closely one next to each other, whereby the arrangement is made in such a manner that quartz tubes having a high heating power alternate with quartz tubes of low heating power.

In the drawings which illustrate several embodiments of the device of the invention:

FIG. 1 illustrates one embodiment of an infrared surface radiator in a side elevation view and partly in section along the broken line Il of FIG. 2,

FIG. 2 is a top elevation view of the infrared surface radiator illustrated in FIG. I, partly broken away,

FIG. 3 is a sectional view of the infrared surface radiator along the line lll-lll of FIG. I.

FIG. 4 is a top elevation view of another infrared surface radiator in which alternately only every second tube is directly heated,

FIG. 5 is a sectional view similar to FIG. 3 of still another embodiment of an infrared surface radiator,

FIG. 6 illustrates a ceramic supporting member employed in the embodiment ofFIG. 5,

FIG. 7 is a sectional view of the ceramic supporting member along the line VII-VII of FIG. 6, and

FIG. 8 is a sectional view of the ceramic supporting member along the line VIII-VIII of FIG. 6.

Referring to the drawings, a longitudinal housing 1, serving also as a reflector, has secured therein at each end a ceramic supporting member 2 by means of screws 3 or the like. In recesses 4 of these ceramic supporting members 2 are carefullymounted the ends of quartz tubes 5a, 5b, 5c, 5d, 5e, 5f and 5g by interpassing of asbestos strips 6. The quartz tubes have mounted therein the coiled heating filaments 7, the connector ends 8 of which are electrically connected to a suitable source of current supply. For preventing the ends 8 to come in contact with the metal housing I the connector ends 8 are passed electrically insulated through slots 9 in the ceramic supporting members 2, and pinch sleeves I0 serve as tension relief members.

The wall of housing I is provided with ceramic sleeves Il serving a lead-in for the connector ends 8.

In the surface radiator shown in the FIGS. 1, 2 and 3 the quartz tubes 5a, 5c, 5e and 5g are provided with a coiled heating filament of high temperature, for instance l,050 C., while the quartz tubes 5b and Sfcontain a coiled heating filament of low temperature, for instance 650 C., but the center quartz tube 511 is not heated.

In the embodiment illustrated in FIG. 4 the tubes 5b, 51! and 5]" are devoid of any heating filament; the tubes are being heated by the adjacent tubes 50, 50, 5e and 5g and radiate themselves with a wavelength in the lower IR range corresponding to their temperature.

FIG. 5 illustrates a modified construction of the surface radiator in which the coiled heating filaments 7 are arranged in flattened or oblong tubular quartz members 12 as shown in cross section. In order to prevent a contact between the two longitudinal coiled heating filaments in the flattened quartz tubes 12, the filaments are separated from each other by an intermediate quartz tube I3 having a circular cross section. In this embodiment there are also arranged indirectly heated quartz tubes I4 of circular cross section between the flattened quartz tubes I2.

The FIGS. 6, 7 and 8 illustrate the particular construction of the ceramic supporting elements. The recess for the reception of a hexagon nut engaged by the screw 3 is designated with IS. Another recess I6 is intended to accommodate the pinch sleeve I0 and I7 is a recess for receiving the head of the ceramic lead-in II.

The surface radiator of the invention may be made in different sizes and shapes. The quartz tube radiators which in accordance with the invention are arranged one next to the other need not necessarily be arranged in a common housing. By assembling a plurality of ceramic parts it would be possible to employ wider housings which in the proposed manner are equipped with quartz tubes.

The individual quartz tubes need not be arranged to be close to each other, as shown in the Figures, but they may also be arranged in spaced relation to one another.

What we claim is:

I. In an infrared surface heater. a housing, a plurality of elongate quartz tubes in said housing in a tierlike formation in substantially parallel relation to each other, coiled heating filaments in said quartz tubes said filaments containing quartz tubes having therein two spaced parallel heating filaments which are kept separated from each other by a quartz tube disposed between the same, an elongate quartz tube devoid of heating filaments disposed adjacent and in substantially parallel relation to at least one of said filaments containing quartz tubes, and means electrically connecting said filaments with a source of electric power.

2. Infrared surface heater according to claim 1, including coiled heating filaments of dissimilar heating power arranged in said quartz tubes.

3. Infrared surface heater according to claim 1, in which the quartz tubes are arranged closely one next to the other and that quartz tubes of high heating power alternate with quartz tubes of lower heating power.

latingly receiving the connector ends of coiled heating filaments arranged in said quartz tubes.

6. Infrared surface heater according to claim I, wherein the filament containing quartz tubes having an oblong cross section.

* m k w UNITED STATES. PATENT VOFFICiE CERTIFICATE OF CORRECTION Patent No. 3627989 Dated December 1 4, 1971 Inv n Albert Heidler and Wolf Dieter Klaus It is certified that error appears in the above-identified patent and that'said Letters Patent are hereby corrected as shown below:

The assignee Thermal Quarr-Schmelze GMBH should be corrected to Thermal Quarg-Schmelze 'GMBH.

Signed end sealed this 11th day of July 1972.

(SEAL) Attest:

EDWARD M. FLETCHER,JR. ROBERT GOTTSCHALK Commissioner of Patents Attesting Officer USCOMM-DC 60376-P69 FORM PO-105O (10-69) us. GOVERNMENT PRINTING OFFICE: nu o-zmmu UNITED STATES PATENT OFFICE. CERTIFICATE OF CORRECTION Patent No. 2627989 I Dated December 14, 1971 Albert Heidler and wolf Dieter Klaus Inventor-(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

The assignee Thermal Quarr-Schmelze GMBH should be corrected to Thermal Quarg-SchmelzeGMBH.

Signed and sealed this 11th day of July 1 972.

(SEAL) Attest:

EDWARD M.FLETCHER,J'R. ROBERT GOTTSCHALK Commissioner of Patents Attesting Officer USCOMM-DC 60376-P69 u.s. GOVERNMENT PRINTING IJFFICE 1969 O366-334 F' ORM PO-105O (10-69) 

1. In an infrared surface heater, a housing, a plurality of elongate quartz tubes in said housing in a tierlike formation in substantially parallel relation to each other, coiled heating filaments in said quartz tubes, said filaments containing quartz tubes having therein two spaced parallel heating filaments which are kept separated from each other by a quartz tube disposed between the same, an elongate quartz tube devoid of heating filaments disposed adjacent and in substantially parallel relation to at least one of said filaments containing quartz tubes, and means electrically connecting said filaments with a source of electric power.
 2. Infrared surface heater according to claim 1, including coiled heating filaments of dissimilar heating power arranged in said quartz tubes.
 3. Infrared surface heater according to claim 1, in which the quartz tubes are arranged closely one next to the other and that quartz tubes of high heating power alternate with quartz tubes of lower heating power.
 4. Infrared surface heater according to claim 1, including ceramic supporting members provided with recesses for supporting therein the end of said quartz tubes.
 5. Infrared surface heater according to claim 1, including ceramic supporting members provided with recesses for supporting therein the end of said quartz tubes, and slots for insulatingly receiving the connector ends of coiled heating filaments arranged in said quartz tubes.
 6. Infrared surface heater according to claim 1, wherein the filament containing quartz tubes having an oblong cross section. 